In wireless receivers, the RF signal that is captured by an antenna of the receiver must be converted to baseband before the information in the signal can be extracted and used by applications. Many wireless communication standards use quadrature modulation to impress information onto an RF carrier. To demodulate such signals, receivers typically use one of a variety of analog processing methods implemented in one of a variety of receiver types, including: heterodyne receivers, super-heterodyne receivers, homodyne receivers, single conversion low intermediate frequency (IF) receivers, and double conversion wideband IF receivers.
Analog receiver designs are typically difficult to modify and tune and must be customized for a particular frequency band of operation. Newer wireless standards, such as the long term evolution (LTE) standard specify many different bands of operation. One drawback of using analog designs for operation over different frequency bands is the non-recurring engineering cost associated with a re-design of a receiver for each and every frequency band.
Further, designs that rely on analog processing suffer from performance degradation caused by electronic noise, temperature variations, voltage variations, manufacturing defects and component aging. Therefore, receiver designs that minimize reliance on analog processing are desired.